twisted reactor calllater实现
twisted reactor calllater实现
1. calllater实现代码
测试源码:
from twisted.internet import reactor
from twisted.internet import defer
def func_1():
print('calllater测试')
time.sleep(5)
print('calllater结束')
# error handle
def test_deferred_a():
#d = test_retrurn_deferred()
reactor.callLater(4, func_1)
reactor.callLater(15, reactor.stop)
reactor.run() if __name__ == '__main__':
test_deferred_a()
1.1. 第一步:调用calllater
reactor.callLater(3, d.callback, 8)
先找到calllater
# <twisted.internet.selectreactor.SelectReactor object at 0x000000CE3BFC72B0>
@implementer(IReactorCore, IReactorTime,
IReactorPluggableResolver,
IReactorPluggableNameResolver, _ISupportsExitSignalCapturing)
class ReactorBase(object):
"""
Default base class for Reactors.
"""
def callLater(self,
_seconds, _f, *args, **kw):
"""See
twisted.internet.interfaces.IReactorTime.callLater.
"""
assert callable(_f), "%s
is not callable" % _f
assert _seconds
>= 0, \
"%s
is not greater than or equal to 0 seconds" % (_seconds,)
tple = DelayedCall(self.seconds()
+ _seconds, _f, args, kw,
self._cancelCallLater,
self._moveCallLaterSooner,
seconds=self.seconds)
self._newTimedCalls.append(tple)
return tple
DelayedCall基本上可以把它当作一个中间类,用于保存一些信息。
结果就是向self._newTimedCalls添加一个定时调用
self._newTimedCalls.append(tple)
可以看一下它的具体内容
_newTimedCalls= <class 'list'>:
[<twisted.internet.base.DelayedCall object at 0x000000CE3C2EA668>]
1.2.
第二步
reactor.run()
跳过一些前置处理内容,直接到mainloop
def mainLoop(self):
while self._started:
try:
while self._started:
# Advance
simulation time in delayed event
# processors.
self.runUntilCurrent()
t2 = self.timeout()
t = self.running and t2
self.doIteration(t)
except:
log.msg("Unexpected
error in main loop.")
log.err()
else:
log.msg('Main loop
terminated.')
进入self.runUntilCurrent()
def runUntilCurrent(self):
"""
运行所有挂起的calls
Run all pending timed calls.
"""
if self.threadCallQueue:
# Keep track of how
many calls we actually make, as we're
# making them, in case another
call is added to the queue
# while we're in this loop.
count = 0
total = len(self.threadCallQueue)
for (f, a,
kw) in self.threadCallQueue:
try:
f(*a, **kw)
except:
log.err()
count += 1
if count ==
total:
break
del self.threadCallQueue[:count]
if self.threadCallQueue:
self.wakeUp()
# insert new delayed
calls now
self._insertNewDelayedCalls()
now = self.seconds()
while self._pendingTimedCalls and (self._pendingTimedCalls[0].time
<= now):
call = heappop(self._pendingTimedCalls)
if call.cancelled:
self._cancellations-=1
continue
if call.delayed_time
> 0:
call.activate_delay()
heappush(self._pendingTimedCalls,
call)
continue
try:
call.called = 1
call.func(*call.args,
**call.kw)
except:
log.deferr()
if hasattr(call, "creator"):
e = "\n"
e += " C:
previous exception occurred in " + \
"a DelayedCall
created here:\n"
e += "
C:"
e += "".join(call.creator).rstrip().replace("\n","\n C:")
e += "\n"
log.msg(e)
if (self._cancellations > 50 and
self._cancellations
> len(self._pendingTimedCalls) >> 1):
self._cancellations
= 0
self._pendingTimedCalls
= [x for x in self._pendingTimedCalls
if not x.cancelled]
heapify(self._pendingTimedCalls)
if self._justStopped:
self._justStopped
= False
self.fireSystemEvent("shutdown")
进入self._insertNewDelayedCalls()
def _insertNewDelayedCalls(self):
for call in self._newTimedCalls:
if call.cancelled:
self._cancellations-=1
else:
call.activate_delay()
heappush(self._pendingTimedCalls,
call)
self._newTimedCalls
= []
从self._newTimedCalls中获取DelayedCall()实例,放入self._pendingTimedCalls
在runUntilCurrent中会调用self._pendingTimedCallsk列表相关对象,也就是执行func_1.
2.
其它
2.1.
代码解析1
heappush(self._pendingTimedCalls,
call)
函数heappush源自heapq.py
def heappush(heap, item):
"""Push
item onto heap, maintaining the heap invariant."""
heap.append(item)
_siftdown(heap, 0, len(heap)-1)
简单点说,它会构建一个有序堆,默认最小堆。
在构建有序堆过程中肯定是要比较int类型了,但call是一个类。
这里要回顾python类的特殊方法了,已有文档,不赘述。
call是DelayedCall类的实例,查看相关代码。
def __le__(self, other):
"""
Implement C{<=} operator between
two L{DelayedCall} instances.
Comparison is based on the C{time}
attribute (unadjusted by the
delayed time).
"""
return self.time
<= other.time
def __lt__(self, other):
"""
Implement C{<} operator between
two L{DelayedCall} instances.
Comparison is based on the C{time}
attribute (unadjusted by the
delayed time).
"""
return self.time
< other.time
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